Pneumatic pressure gauge



J. H. BECKER PNEUMATIC PRESSURE GAUGE Filed July 19, 1932 oct. s, 1935.V

Patented Oct. 8, 1935 UNITED STATES lPATENT OFFICE PNEUMATIC PRESSUREGAUGE Application July- 19, 1932, Serial No. 623,362

3 Claims. (Cl. 73-111') l This invention .relates generally to pressuregauges utilized in the inflation of pneumatic tires. More particularlyit relates to devices of this character' which are attached to the endof 5 an air hose, for ready application to the valve stem of anautomobile tire.

It is a general object of the invention to devise an improved form ofpressure gauge of the above character, which will give comparativelyaccurate pressure readings when employed in connection with both highandlow pressure automobile and truck tires.

It is a further object of the invention, to provide in a pressure gaugeof the above character,

means whereby ready adjustments can be made to afford accuracy, both atthe time of assembling the parts in manufacture, and after the gauge hasbeen in use.

Another object of the invention is to provide 2 a novel form of valvecontrol means in a device of the above character, whereby an operatorcan deflate the tire Without removing the device from the valve stem.

Further objects of the invention will appear 25 from the followingdescription in which the preferred embodiment of the invention has beenset forth in detail in conjunction with the accompanying drawing. Itwill be understood that the appended claims are to be accorded a rangeof 45 sists of a body I0 formed of suitable material,

such as a casting of aluminum. Carried by the body I0, there is asuitable fitting I I, adapted to be connectedy to the end of a pneumatichose.

For applying the device to a tire stem of a tire 50 to be inflated, Iprovide a suitable connector I2,

which is attached to a fitting I3 by a short flexible hose section I4.

To alford novel pressure indicating means,

body Ill is bored to form a cylinder I6, and slid- 55 ably fitted withincylinder I6, there is a suitable equivalents consistent with the stateof the priorY pneumatic plunger or piston I1. Piston I1 is shownprovided with a cup Washer I8, to minimize leakage between the pistonand the walls of cylinder I6. It will also be noted that piston I1 isrelatively long, being provided with an ex- A5 tended sleeve I9. Thissleeve carries a lug 2|, which forms an indicating member. By referenceto Fig. 1 it will be seen that indicating member. 2l is accommodated inan elongated slot 22, and that it is associated with a graduated 10scale 23. The edge portion of scale 23 is releasably clamped to the bodyIIJ, by means of a frame 24, this construction affording an adjustmentof the scale relative to the body I0 and relative to the indicatingmember 2|. Scale 23 is prefer- 15 ably provided with one set of loWpressure graduations 23a, and another set of high pressure graduations23h.

Extending longitudinally of body III, and axially of the cylinder I6,there is a guide member 26 which is preferably in the form of a tube.One end of tube 26 is provided with an enlarged annular portion 21,serving as a limiting stop for movement of piston l1 in one direction.One face of this enlargement is also sealed With re- 25 spect to thebody I0, as by means of an interposed gasket 28. That portion of tube 26which extends beyond enlargement 21, is threaded for engagement with aninternally threaded closure lscrew 3I. The other end of tube 26 isprovided 30 Vwith threaded engagement 32 with fitting I3.

'I'he passageway33, in tube 26, is at its one end in free communicationwith hose I4 and connector I2, andat its other end in free communicationwith a port 34 formed in body I0. Piston I1 35 is also provided with aninternal sleeve 36, in addition to the external sleeve I9, and thisinternal sleeve has a fairly snug sliding fit upon tube 26. In Fig. 2piston I1 has been shown in its retracted or zero position. In order toyieldingly 40 urge the piston toward this position, I provide springmeans which preferably utilizes two springs of differentcharacteristics, which are arranged in series, so that one spring actsupon the other. Thus as shown in Fig. 2, I provide two springs 31 and38,which are preferably of spring wire coiled helicoidally. Spring 31 isrelatively `stronger than spring 38, so that, for a given force uponspring 31 tending to compress it, the amount of compression will besubstantially less than the amount of compression of spring 38 under thesame force. One end of spring 31is shown seated upon piston I1, and theremote end of spring 38 is shown seated upon fitting I3. The adjacentends of springs. 31 and -38 are shown seated upon 55 an annular follower39, which in turn is slidably retained upon tube 25. While the action ofsuch a compound spring will be presently explained in greater detail, itmay be pointed out that when piston I1 is moved toward a pressureindicating position, the weaker spring 3B is first compressed to agreater extent than the stronger spring 31. However after compression ofspring` 38 is no longer possible, further movement of piston I 1 byhigher pneumatic pressures is resisted by Adeflection of spring 31.

In the use of spring means such as explained above I have found that thecorresponding high and low pressure graduations upon scale 23, cannot beequally spaced, if in the operation of the indicator the weaker springis at times fully compressed. Likewise in practice inaccuracies areinvariably encountered if full compression of the weaker spring ispermitted. I therefore provide limiting means in conjunction with spring38, to limit compression of this spring to an extent substantially lessthan full compression of the Same. By full compression I have referenceto such a degree of compression as will cause the convolutions of thesprings to directly contact one upon the other. As a simple form ofcompression limiting means, I have Shown a shoulder 4I formed upon tube26. This shoulder is adapted to engage the end face or shoulder 42,formed upon the annular follower 39. Follower 39 is so proportioned, andshoulder 4I so positioned, that when shoulders 4I and 42y are inengagement, spring 38 is not fully compressed. Therefore for the fullpermitted range of operation of spring 38, its deflection will besubstantially in direct proportion to compressional forces imposed uponthe same.

The mounting of the springs 31 and 38 and arrangement of parts describedabove, enables an adjustment of the tension upon the spring means,without eifecting a corresponding change in the zero adjustment of theindicating member 2 I. In this connection it will be noted that tting I3is ordinarily locked against rotation with respect to the body I8, byset screw 44. Upon loosening set screw 44, turning of fitting I3 servesYto traverse the same like a nut upon the threaded end portion of tube25, so that more or less initial tension is imposed upon springs 31 and38.

In addition to the novel indicating means which has been previouslydescribed, I provide in conjunction with my device a manual operator4,8, and valve means actuated by the operator 46, designated generallyat 41. The particular form of operator 46 illustrated consists of abutton shaped portion which can be readily engaged by the nger of theoperator, and which is carried on one end of a stem 48. Stem 48 isslidably mounted within a bore 49, formed within the body I0. A lock pin5I, accommodated by a iiattened portion 52 formed on stem 48, limitssliding movement, and prevents accidental removal. Extending from theinner end of stem 48, there is a pin 53, slidably fitted within a bore54 formed. axially of bore 49. A compression spring 55 serves to urgethe stem 48 outwardly.

Valve means 41 is formed of two principal operating members, one being aprimary valve member 58, and the other being a secondary valve member51. Valve member 55 is provided with a cylindrical portion 58 slidablewithin a cylindrical bore 59, with a valve surface 6I, and also with apin 62 projecting into bore 54. Valve surface 6I is adapted to engagewith a stationary valve seat 63. It will be noted that the cylindricalportion 58 is interrupted by a port 64, for a purpose to be presentlyexplained. Bore 54 is in communication with the atmosphere thru a ventport 55, and bore 59 is in communication with the pneumatic chamber 61behind piston I1, by means of a 5 port 58.

The secondary valve member 51 cooperates with a stationary seat member69. It is also urged toward closed position, by a compression spring 1IIt will be noted that seat member 69 is 10 so constructed, that theinterior of bore 59 is always in communication with port 34. Likewisewhen the secondary valve member 51 is in open position, air pressurefrom the hose connected to fitting II, is free to iiow thru port 34, andthus 15 thruv passage 33 to connector I2 and to the tire being inated.

In .order to cooperate with the secondary valve member 51, the primaryvalve member 55 is also provided with an inwardly projecting pin 13, and20 a valve surface 14. When valve member 55 is moved to its limitingposition toward the right as viewed in Fig. 2, pin 13 forces secondaryvalve member 51 to open position, and at the same time valve surface 1dseals upon the seating sur- 25 face 15 provided on the seat member 88.

Operation of my device is as followsr-Assuming that the operator wishesto inflate a tire, the first operation is to apply the connector i2 tothe valve stem, while the actuator 45 is in the posi- 30 tionillustrated in Fig. 2. Air from the tire will immediately flow thru'passage 33 to the pressure chamber 51 behind piston I1, by way of port35, bore 59, and port 58. The pressure thus imposed upon piston I1, willforce this piston against the 35 pressure of springs 31 and 38, and the.corresponding position of indicator 2l with respect to scale 23, willapprise the operator of the tire pressure.

If the tire pressure is too low, the operator then forces actuator 46inwardly to the limit of its 40 movement, thus causing the primary valvemember 55 to open the secondary valve member 51, thus permitting highpressure air from the hose connected to fitting II, to ilow thru port3,13, and thru passage 33 to the tire. At the same time the 45 seatingof surface 14 of primary valve member 55, upon the stationary seatingsurface 15, will prevent application of high pressure air to thepressure chamber 6,1. In fact at this time pressure chamber 81 will bevented to the atmosphere, 50 thru ports 55 and 68. While the tire isbeing. inated, the operator may at any time secure an indication of thetire pressure, merely by releasing all manual force upon the actuator46. While a pressure indication is being taken, a small 55 amount of airwill be continuously bled thru the clearance between tube 26 and sleeve35. In

ythe event a greater pressure than desired is applied to the tire, theoperator can vent the tire pressure to the atmosphere, merely byreturning 60 the actuator 45 to an intermediate. position. In suchposition primary valve 55 will have its valve surface 5I disengaged'from the seat S3, to permit a flow of air by way of port 34, bore 55,and port 66, to the atmosphere.V Likewise during suchl an 55.

ton and its cooperating parts, and between the follower 39 and tube 26.It will be noted that this follower is not in contact with the adjacentportion of body IU, and that it retains the intermediate portions ofsprings 31 and 38 out of contact with tube 26 and the body.

I claim:

1. In a pressure gauge to be used in the inflation of both low and highpressure tires, a pneumatic cylinder, a guide member extending1ongitudinally of and centrally of the cylinder, a piston slidablydisposed within the cylinder and upon said guide member, means forestablishing communication between the space at one side of the pistonand the tire to be inated, whereby pneumatic pressure on the pistontends to move the same in one direction, spring means serving toresiliently urge the piston in the opposite direction, said spring meanscomprising a pair of coiled compression springs connected in serieswhereby one spring acts upon the other, one spring being substantiallyweaker than the other, and a follower for retaining the adjacent ends ofsaid springs with respect to said guide members.

2. In a pressure gauge to be used in the inflation of both low and highpressure tires, a cylinder, a guide member extending longitudinally oithe cylinder and centrally of the cylinder, a piston slidably disposedwithin the cylinder and upon said guide member, means for establishingcommunication between the space at one side of the piston and the tireto be inflated, whereby pneumatic pressure on the piston will tend tomove the same in one direction, an indicating member movable togetherwith said piston, a low and high pressure graduated scale associatedwith said indicating member, spring means serving to resiliently urgethe piston in a direction opposite to that in which the piston is urgedby said pneumatic pressure, said spring means comprising 5 a pair ofcoiled compression springs connected in series whereby one spring actsupon the other, one spring being substantially weaker than the other,and means for limiting compression of the weaker spring to an extentsubstantially less than the full compression of the same, said lastmeans including a follower slidably mounted upon the guide member andserving to engage the adjacent ends of the spring.

3. In a pressure gauge to be used in the inlating of both low and highpressure tires, a body formed to provide a pneumatic cylinder, a guidetube mounted upon said body and extending longitudinally and centrallyof the cylinder, one end of said tube being adapted to be placed incommunication with a tire to be inflated, a piston slidably disposedwithin the cylinder and upon said guide tube, means for establishingcommunication between the space at one side of the piston and the otherend of said guide tube, whereby pneumatic pressure on the piston tendsto move the same in one direction, spring means serving to resilientlyurge the piston in the opposite direction, said spring means comprisinga'pair of coiled compression springs connected in series whereby onespring acts upon the other, one spring being substantially weaker thanthe other, and a follower for retaining the adjacent ends of said springwith respect to said guide tube.

J ULIUS H. BECKER.

